4887-88-1Relevant academic research and scientific papers
Methanol as the C1source: Redox coupling of nitrobenzenes and alcohols for the synthesis of benzimidazoles
An, Jie,Lai, Zemin,Li, Hengzhao,Peng, Mengqi,Sun, Yanhao,Yan, Zihan,Yang, Ruoyan,Zhang, Yuntong
supporting information, p. 748 - 753 (2022/02/02)
We present an operationally simple redox coupling for the synthesis of N-1 substituted benzimidazoles using feedstock building block 2-nitroaniline derivatives as the precursors and methanol as the C1 source. Higher atom, step, and redox economies and exc
One-Pot Transformation of Lignin and Lignin Model Compounds into Benzimidazoles
Guo, Tao,He, Jianghua,Liu, Tianwei,Zhang, Yuetao
supporting information, (2022/02/07)
It is a challenging task to simultaneously achieve selective depolymerization and valorization of lignin due to their complex structure and relatively stable bonds. We herein report an efficient depolymerization strategy that employs 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as oxidant/catalyst to selectively convert different oxidized lignin models to a wide variety of 2-phenylbenzimidazole-based compounds in up to 94 % yields, by reacting with o-phenylenediamines with varied substituents. This method could take full advantage of both Cβ and/or Cγ atom in lignin structure to furnish the desirable products instead of forming byproducts, thus exhibiting high atom economy. Furthermore, this strategy can effectively transform both the oxidized hardwood (birch) and softwood (pine) lignin into the corresponding degradation products in up to 45 wt% and 30 wt%, respectively. Through a “one-pot” process, we have successfully realized the oxidation/depolymerization/valorization of natural birch lignin at the same time and produced the benzimidazole derivatives in up to 67 wt% total yields.
Sustainable Synthesis of 2-Hydroxymethylbenzimidazoles using D-Fructose as a C2 Synthon
Raja, Dineshkumar,Philips, Abigail,Sundaramurthy, Devikala,Chandru Senadi, Gopal
supporting information, p. 3754 - 3759 (2021/10/14)
D-fructose, a biomass-derived carbohydrate has been identified as an environmentally benign C2 synthon in the preparation of synthetically useful 2-hydroxymethylbenzimidazole derivatives by coupling with 1,2-phenylenediamines. Proof of concept was established by synthesizing 23 examples using BF3.OEt2 (20 mol%), TBHP (5.5 M, decane) (1.0 equiv.) in CH3CN at 90 °C for 1 h. The pivotal features of this method include metal-free conditions, short time, good functional group tolerance, gram scale feasibility and the synthesis of benzimidazole fused 1,4-oxazine. Control studies with conventional C2 synthons did not produce the desired product, thus suggesting a new reaction pathway from D-fructose.
Highly Efficient and Catalyst-Free Synthesis of Benzimidazoles in Aqueous Media
Huang, W.-H.,Jin, Y.-J.,Ma, L.-F.,Wu, Y.,Zhou, L.-H.
, p. 825 - 830 (2021/06/12)
Abstract: A convenient and highly efficient, catalysts-free synthesis of benzimidazoles in an aqueous medium has been developed. The conditions of the synthesis were optimized, and its scope was successfully extended to various substrates with good to excellent yields. The experimental procedure is simple, and the products can be isolated by filtration followed by recrystallization from water.
Hetero- A nd Homobimetallic Complexes Bridged by a Bis(NHC) Ligand: Synthesis via Selective Sequential Metalation and Catalytic Applications in Tandem Organic Transformations
Nishad, Rajeev C.,Kumar, Shashi,Rit, Arnab
, p. 915 - 926 (2021/05/04)
A (bis)azolium salt [L1-H2]Br2 (5), synthesized following multistep procedures, was realized to be a suitable platform for accessing the bis(NHC) ligand supported heterobimetallic IrIII-M (M = PdII/AuI) complexes via a sequential metalation strategy for their potential catalytic applications in one-pot tandem organic transformations. First, the reaction of 5 with 0.5 equiv of [Ir(Cp-)Cl2]2 selectively yielded a monometallic IrIII complex 6, which was further metalated using Pd(OAc)2/NaOAc to afford the heterobimetallic IrIII-PdII complex 7. On the other hand, complex 6 was reacted with Ag2O, followed by transmetalation with [Au(SMe2)Cl] in a one-pot manner, to yield the IrIII-AuI complex 8. Further, the related homobimetallic IrIII and PdII complexes 9 and 10, respectively, have also been synthesized directly from [L1-H2]Br2. All the homo/heterobimetallic complexes have been well-characterized by multinuclear NMR spectroscopy, ESI-mass spectrometry, and via single-crystal X-ray diffraction studies of the complexes 7, 8, and 10. The heterobimetallic IrIII-PdII complex 7 has been tested as a catalyst for three one-pot tandem catalytic reactions: (a) Suzuki-Miyaura coupling and transfer hydrogenation of ketones, (b) hydrodefluorination and transfer hydrogenation of ketones, and (c) hydrodehalogenation and transfer hydrogenation of imines. Importantly, the catalytic activity of heterobimetallic complex 7 in the above-mentioned reactions was found to be better than the mixture of their corresponding homobimetallic counterparts 9 and 10, keeping the concentration of the metal centers constant. These observations affirm some sort of cooperativity between the two metal centers (Ir and Pd) connected via a single ligand frame in 7 when catalytic activity is concerned, which thus constitutes a superior catalytic system than that of the cases where two separate metal complexes (hence, the two metal centers are not connected by a single ligand framework) are used.
Poly(3-hexylthiophene)s Functionalized with N-Heterocyclic Carbenes as Robust and Conductive Ligands for the Stabilization of Gold Nanoparticles
Sun, Ningwei,Zhang, Shi-Tong,Simon, Frank,Steiner, Anja Maria,Schubert, Jonas,Du, Yixuan,Qiao, Zhi,Fery, Andreas,Lissel, Franziska
supporting information, p. 3912 - 3917 (2020/12/30)
Recently, N-heterocyclic carbenes (NHCs) are explored as anchor groups to bind organic ligands to colloidal gold (i.e. gold nanoparticles, Au NPs), yet these efforts are confined to non-conjugated ligands so far—that is, focused solely on exploiting the s
Method for synthesizing benzimidazole from carbon dioxide and o-phenylenediamine compound
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Paragraph 0033-0036, (2021/06/06)
The invention discloses a method for synthesizing benzimidazole from carbon dioxide and an o-phenylenediamine compound, the method is characterized in that an amino-containing functionalized ordered mesoporous polymer is used as a catalyst, o-phenylenediamine and carbon dioxide are used as raw materials, dimethylaminoborane is used as a hydrogen reduction reagent, carbon dioxide and the o-phenylenediamine compound are catalyzed to react in an NMP solvent to generate a benzimidazole compound, wherein the dosage of a catalyst is 0.01-1mol% based on the nitrogen content of the o-phenylenediamine compound; the filling pressure of the carbon dioxide is 0.1-2MPa; the reaction temperature is 60-180DEG C; the molar ratio of the catalyst to the NMP is 1:50-100. Compared with the prior art, the catalyst has the advantages of simple preparation, high catalytic activity, capability of catalyzing the reaction of carbon dioxide and the o-phenylenediamine compound under mild conditions to generate benzimidazole and derivatives thereof, and the like.
Reductive cyclization of o-phenylenediamine with CO2 and BH3NH3 to synthesize 1H-benzoimidazole derivatives
Han, Limin,Hong, Hailong,Li, Xiao,Yang, Yue,Zhang, Junhua,Zhu, Ning
supporting information, (2021/09/28)
A simple and green protocol was developed for the reductive cyclization of o-phenylenediamine with CO2 and BH3NH3 to yield 1H-benzimidazole. The desired 1H-benzimidazole derivatives were produced under mild conditions. Mechanism investigation indicated that the coordination of o-phenylenediamine with the boron atom of BH3NH3 promoted the transfer of the formyl group to form a stable intermediate, which facilitated the intramolecular nucleophilic addition-elimination for the formation of target product. In this process, BH3NH3 served multifunctional roles, acting as a reducing agent and a formylation catalyst.
Highly efficient one pot synthesis of benzimidazoles from 2-nitroaniline and PhSiH3 as reducing agent catalyzed by Pd/C as a heterogeneous catalyst
Phatake, Vishal V.,Bhanage, Bhalchandra M.
, (2021/03/15)
This work reports an efficient route for the synthesis of benzimidazole from o-nitroaniline in the presence of carbon dioxide atmosphere, PhSiH3 as a reducing agent catalyzed by Pd/C as a catalyst. Benzimidazoles have become the focus of organic chemists, as benzimidazole is an important intermediate in medicinal chemistry. We have developed more efficient route for the synthesis benzimidazole and various substituted benzimidazoles have been synthesized in good to excellent yield. The TBD (1,5,7-Triazabicyclo [4.4.0] dec-5-ene) is selected as a base as it promotes the CO2 insertion. Benzimidazoles were synthesized through reduction of nitro group followed by cyclization of amine using CO2 as a carbon source. Moreover, the Pd/C catalyst can be recycled up to five recycle run without significant changes in the yield of the product.
Endogenous X-C=O species enable catalyst-free formylation prerequisite for CO2reductive upgrading
Dai, Wenshuai,Li, Hu,Saravanamurugan, Shunmugavel,Wu, Hongguo,Yang, Song
, p. 5822 - 5832 (2020/10/21)
CO2, the main component of greenhouse gas, is currently developed as a promising surrogate of carbon feedstock. Among various conversion routes, CO2undergoing catalytic reduction can furnish hydrogen/energy carriers and value-added chemicals, while specific metal-containing catalysts or organocatalysts are often prerequisite for smooth proceeding of the involved reaction processes. In this work, both formic acid and N-containing benzoheterocyclic compounds (including various benzimidazoles, benzothiazole, and benzoxazole) along with silanols could be synthesized with high yields (>90%) from catalyst-free reductive upgrading of CO2under mild conditions (50 °C). The endogenous X-CO species, derived from the N-methyl-substituted amide-based solvent [Me2N-C(O)-R], especially PolarClean, and O-formyl group [O-C(O)-H] of in situ formed silyl formate, were found to play a prominent promotional role in the activation of the used hydrosilane for reductive CO2insertion, as demonstrated by density functional theory (DFT) calculations and isotopic labeling experiments. Moreover, reaction mechanisms and condition-based sensitivity assessment were also delineated.
